South Buffalo Fire Chief Randy Brozenick said the boy, who was wearing a life vest, managed to swim to the boat and was pulled from the water.

"They both had life jackets on, but the gentleman that went under apparently did not have it clipped together, so he had it on but it wasn't clipped on," Brozenick said.

The under currents on Sunday were described as strong, and afternoon storms made it tough for search crews who spent hours trying to find the man between locks 5 and 6.

"They have a camp across on the other side of the river and they had some family there," said Brozenick. "Some of the family was out there when this happened, on the pontoon boat. Actually, he was riding around the pontoon boat, so they actually witnessed what happened."

A life jacket was reportedly found about a mile downriver from where the man was last seen.

Experienced divers said the murkiness, debris and dips on the river floor have made the search one of their toughest yet.

“That’s what they're saying. They've never seen a river like that. So much differences in height,” Brozenick said.

Brozenick said that when the divers get to the bottom of the river, they have zero visibility. He said they have to use just their hands and other senses to search.

“There’s also some debris down there and that becomes a concern of ours for the safety of the drivers getting tangled up in some of the debris. There's some trees and stuff that are down there,” Brozenick said.

"This river has been dredged many times," said DeAngelis, whose son was a part of the search team Sunday. "There's places out there where they were searching that's 35, 40 feet deep."

It's unclear what caused Uzmack to lose control of the watercraft.

"A jet ski is a motorcycle on the water," said DeAngelis. "It turns real quick, it flips over, people fall off, stuff like that, so if you're not a swimmer, you probably shouldn't be out there at all -- even with a jacket."

Photos: Jet skier goes missing in Allegheny River

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A man fell off a jet ski and went underwater Sunday on the Allegheny River in South Buffalo Township, Armstrong County.

UNDED BY WTAE-TV BREAKING RIGHT NOW, A BODY IS PULLED FROM THE ALLEGHENY RIVER, RIGHT NEAR THE SITE OF A WEEKEND JET SKI ACCIDENT. THE CORONER IS ON THE SCENE RIGHT NOW. THIS IS ON THE RIVER'S EAST SIDE IN BUFFALO TOWNSHIP RIGHT NEAR SHELLY PARK. CREWS HAVE BEEN SEARCHING FOR 40-YEAR-OLD THOMAS UZMAK SINCE HE FELL INTO THE RIVER ON SUNDAY. HIS 12-YEAR-OLD NEPHEW WAS WITH HIM AT THE TIME. HE WAS ABLE TO SWIM TO A NEARBY BOAT. FAMILY MEMBERS SAY UZMAK WAS WEARING A LIFE JACKET, BUT IT WASN'T BUCKLED.

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